In recent years, there is a CDMA (Code Division Multiple Access) system as one of communication systems used for wireless communication of a cellular phone, which is developing rapidly, and the like. Further, there is also a W-CDMA (Wideband Code Division Multiple Access) system that can further improve use efficiency of frequencies (hereinafter, in this specification, in the case of stating a CDMA system, the W-CDMA system is included).
In the CDMA system, different digital codes are assigned to cellular phones of transmitters, respectively. Then, an audio signal of one transmitter and an audio signal of another transmitter are integrated to transmit it as one audio signal. In the CDMA system, since a signal integrated so as to share a code between a cellular phone and a base station is decomposed again, simplification of a communication system is possible.
However, in the CDMA system in which all users use a carrier wave of the same frequency, a problem that, in the case where each cellular phone outputs a radio wave with the same transmitted power regardless of a distance from a base station, a radio wave from a nearer cellular phone has too high intensity and a base station cannot thereby separate a signal from a farther cellular phone. Therefore, there is a need that each cellular phone carries out transmitted power control for keeping transmitted power to a minimum. The transmitted power control is effective to keep interference electric energy low, and moreover, can bring about increase in subscriber capacity of the system. Cellular phones generally have a function such as TPC (Transmit Power Control) to hold electric power consumption to a minimum necessary level.
A wireless communication system in which a mobile device such as a cellular phone carries out transmitted power control, thereby achieving more stable handover is disclosed in Japanese Patent Application Publication No. 2005-184708 (Paragraph 0037, FIG. 7). Hereinafter, Japanese Patent Application Publication No. 2005-184708 is stated as Patent Document 1. In the wireless communication system described in Patent Document 1, when to carry out integration between sectors, control of a TPC bit and transmitted power control are carried out in every wireless link (Radio Link; hereinafter, abbreviated to an “RL”). As a result, it is possible to achieve the wireless communication system in which communication quality is improved.